PRIMARY STRUCTURE-ANALYSIS OF TMV VACCINE STRAIN-V-69

A random set of cDNA fragments were synthesized on genomic RNA of TMV vaccine strain V-69, using random primers and reverse transcriptase. F ollowing synthesis of double-stranded cDNA, they were cloned into the pUC-19 plasmid; and 28 clones were sequenced (insert size 100 - 500 bp ). High nucleotide sequence homology of V-69 (more than 95%) was shown only with tomato strain TMV-L [1]. Sequenced clones represent 54% of the genome (50% of the replicase gene, 98% of the transport protein ge ne, and 60% of the coat protein gene). In this genome region, 24 base substitutions were revealed, as compared to the wild-type TMV-L sequen ce. Six base substitutions resulted in changes in corresponding amino acid codons. No substitutions coincided with those discovered in the r elated TMV vaccine strain L11A [2], while two substitutions in the rep licase gene were identical to those found in TMV strain Lta 1 [3], whi ch is capable of overcoming protection in tomatoes with the resistance gene Tm-1.